Williamson home constructed amplifier, c 1949.
© Science Museum / Science & Society Picture Library
Amplifiers are used in radios to boost the strength of the incoming signal. Built to a design proposed by D T N Williamson in a magazine called 'Wireles World' in 1947, this amplifier represented a major step towards domestic high-fidelity sound reproduction. It used two valves to drive the loudspeaker, one pushing, the other pulling, an arrangement similar to that still used in modern amplifiers. Like most amplifiers of the time, it was constructed at home from components purchased separately.